Wireless telecommunications apparatus and methods

ABSTRACT

A retransmission method for use in a telecommunications system, the method comprising: transmitting, to a terminal, first data in a set of identified resources allocated for the transmission of the first data; identifying that a portion of the identified resources has been used to transmit data other than the first data; and retransmitting a subset of the first data, the subset of the first data comprising the portion of the first data that was previously scheduled to be transmitted in the portion of the identified resources.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on PCT filing PCT/EP2017/072025, filedSep. 1, 2017 which claims priority to EP 16191978.2, filed Sep. 30,2016, the entire contents of which are incorporated herein by reference.

FIELD

The present disclosure relates to wireless telecommunicationsapparatuses and methods.

BACKGROUND

The present application claims the Paris Convention priority of Europeanpatent application 16191978.2 the contents of which are hereinincorporated by reference.

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Third and fourth generation mobile telecommunication systems, such asthose based on the 3GPP defined UMTS and Long Term Evolution (LTE)architecture are able to support more sophisticated services than simplevoice and messaging services offered by previous generations of mobiletelecommunication systems. For example, with the improved radiointerface and enhanced data rates provided by LTE systems, a user isable to enjoy high data rate applications such as mobile video streamingand mobile video conferencing that would previously only have beenavailable via a fixed line data connection. The demand to deploy thirdand fourth generation networks is therefore strong and the coverage areaof these networks, i.e. geographic locations where access to thenetworks is possible, is expected to increase rapidly. However, whilstfourth generation networks can support communications at high data rateand low latencies from devices such as smart phones and tabletcomputers, it is expected that future wireless communications networkswill be expected to efficiently support communications with a much widerrange of devices associated with a wider range of data traffic profiles,for example including reduced complexity devices, machine typecommunication devices, high resolution video displays and virtualreality headsets. Some of these different types of devices may bedeployed in very large numbers, for example low complexity devices forsupporting the “The Internet of Things”, and may typically be associatedwith the transmissions of relatively small amounts of data withrelatively high latency tolerance, whereas other types of device, forexample supporting high-definition video streaming, may be associatedwith transmissions of relatively large amounts of data with relativelylow latency tolerance.

There is therefore expected to be a desire for future wirelesscommunications networks, which may be referred to as 5G or new radio(NR) system/new radio access technology (RAT), networks, to efficientlysupport connectivity for a wide range of devices associated withdifferent applications with different characteristic data trafficprofiles, resulting in different devices having different operatingcharacteristics/requirements, such as:

-   -   High latency tolerance    -   High data rates    -   Millimetre wave spectrum use    -   High density of network nodes (e.g. small cell and relay nodes)    -   Large system capacity    -   Large numbers of devices (e.g. MTC devices/Internet of Things        devices)    -   High reliability (e.g. for vehicle safety applications, such as        self-driving cars).    -   Low device cost and energy consumption    -   Flexible spectrum usage    -   Flexible mobility    -   Ultra-reliable and Low latency

A 3GPP Study Item (SI) on New Radio Access Technology (NR) [1] has beenproposed for studying and developing a new Radio Access Technology (RAT)for such a next generation wireless communication system. The new RAT isexpected to operate in a large range of frequencies and it is expectedto cover a broad range of use cases. Example use cases that areconsidered under this SI are:

-   -   Enhanced Mobile Broadband (eMBB)    -   Massive Machine Type Communications (mMTC)    -   Ultra Reliable & Low Latency Communications (URLLC)

eMBB services are typically high capacity services with a requirement tosupport up to 20 Gb/s. For efficient transmission of large amounts ofdata at high throughput, eMBB services are expected to use a longscheduling time so as to minimise the overhead, where scheduling timerefers to the time available for data transmission between allocations.In other words, eMBB services are expected to have relatively infrequentallocation messages and to have longer time period allocated to datatransmission in-between allocation messages.

On the other hand URLLC services are low latency services, wherein thelatency is measured from the ingress of a layer 2 packet to its egressfrom the network, with a proposed target of 1 ms. URLLC data isgenerally expected to be short such that smaller scheduling times aregenerally expected compared to eMBB transmissions. As the skilled personwill understand, eMBB transmissions and URLLC transmissions havedifferent requirements and expectations, wherein high capacity and lowoverhead is desired for one while low latency is desired for the other.

It is therefore challenging to conceive a system which can accommodateboth needs and where these two very different types of transmissions canbe transmitted in a satisfactory manner. In view of this, there is adesire to provide arrangements and systems where high capacity and lowlatency transmissions can be communicated at the same time while tryingto optimise resources utilisation for the system as a whole and for eachtype of transmission. In particular, in cases where there is a conflictbetween two transmissions, it could be beneficial to provide anarrangement where any repair mechanism would assist with an efficientuse of the resources within the network.

SUMMARY

The present disclosure can assist addressing or mitigating at least someof the issues discussed above.

Respective aspects and features of the present disclosure are defined inthe appended claims.

From one perspective, there has been provided a retransmission methodfor use in a telecommunications system, the method comprising:transmitting, to a terminal, first data in a set of identified resourcesallocated for the transmission of the first data; identifying that aportion of the identified resources has been used to transmit data otherthan the first data; and retransmitting a subset of the first data, thesubset of the first data comprising the portion of the first data thatwas previously scheduled to be transmitted in the portion of theidentified resources. By retransmitting the subset of the first data,rather than all of the first data, the retransmission procedure may bemade more efficient. It is also noteworthy that by “retransmitting” itis meant that the transmission if attempted for the second time but, asthe skilled person will appreciate, in a case where the transmission ofthe first data was punctured by the other data, some or all of thesubset of the data may not have been transmitted at all in the originaltime unit. In this case it can be transmitted for the first time in asubsequent time unit (“retransmitted”).

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology. The described embodiments,together with further advantages, will be best understood by referenceto the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 schematically represents some elements of a conventionalLTE-based mobile telecommunications network/system;

FIG. 2 schematically represents some elements of another type ofwireless telecommunications network/system;

FIG. 3 schematically represents an example eMBB transmission inaccordance with the present disclosure;

FIG. 4 schematically represents an example URLLC transmission inaccordance with the present disclosure;

FIG. 5 schematically represents an example multiplexing of eMBB andURLLC transmissions;

FIG. 6 illustrates an example of a transmission repair using HARQ;

FIG. 7 illustrates an example of a transmission repair according to thepresent disclosure;

FIG. 8 illustrates an example of a transmission repair according to thepresent disclosure;

FIG. 9 illustrates an example of a transmission repair according to thepresent disclosure;

FIG. 10 illustrates an example of a transmission repair according to thepresent disclosure;

FIG. 11 illustrates an example of a transmission repair according to thepresent disclosure;

FIG. 12 illustrates an example of a transmission repair according to thepresent disclosure;

FIG. 13 illustrates example additions of extra resources for aretransmission;

FIG. 14 illustrates an example rate-matching method for use in aretransmission;

FIG. 15 illustrates an example rate-matching method for use in aretransmission; and

FIG. 16 illustrates an example rate-matching method for use in aretransmission.

DESCRIPTION OF EXAMPLES

FIG. 1 is a schematic diagram illustrating a network architecture for anLTE-based wireless mobile telecommunications network/system 100. Variouselements of FIG. 1 and their respective modes of operation arewell-known and defined in the relevant standards administered by the3GPP (RTM) body, and also described in many books on the subject, forexample, Holma H. and Toskala A [2]. It will be appreciated thatoperational aspects of the telecommunications network represented inFIG. 1, and of other networks discussed herein in accordance withembodiments of the disclosure, which are not specifically described (forexample in relation to specific communication protocols and physicalchannels for communicating between different elements) may beimplemented in accordance with any known techniques, for exampleaccording to currently used approaches for implementing such operationalaspects of wireless telecommunications systems, e.g. in accordance withthe relevant standards.

The network 100 includes a plurality of base stations 101 connected to acore network 102. Each base station provides a coverage area 103 (i.e. acell) within which data can be communicated to and from terminal devices104. Data is transmitted from base stations 101 to terminal devices 104within their respective coverage areas 103 via a radio downlink. Data istransmitted from terminal devices 104 to the base stations 101 via aradio uplink. The core network 102 routes data to and from the terminaldevices 104 via the respective base stations 101 and provides functionssuch as authentication, mobility management, charging and so on.Terminal devices may also be referred to as mobile stations, userequipment (UE), user terminal, mobile radio, communications device, andso forth. Base stations, which are an example of network infrastructureequipment, may also be referred to as transceiverstations/nodeBs/e-nodeBs, and so forth.

FIG. 2 is a schematic diagram illustrating a network architecture for anew RAT wireless mobile telecommunications network/system 300 based onpreviously proposed approaches and which may be adapted to providefunctionality in accordance with embodiments of the disclosure describedherein. The new RAT network 300 represented in FIG. 2 comprises a firstcommunication cell 301 and a second communication cell 302. Eachcommunication cell 301, 302, comprises a controlling node (centralisedunit) 321, 322 in communication with a core network component 500 over arespective wired or wireless link 351, 352. The respective controllingnodes 321, 322 are also each in communication with a plurality ofdistributed units (radio access nodes/remote transmission and receptionpoints (TRPs)) 311, 312 in their respective cells. Again, thesecommunications may be over respective wired or wireless links. Thedistributed units 311, 312 are responsible for providing the radioaccess interface for terminal devices connected to the network. Eachdistributed unit 311, 312 has a coverage area (radio access footprint)341, 342 which together define the coverage of the respectivecommunication cells 301, 302.

In terms of broad top-level functionality, the core network component500 of the new RAT telecommunications system represented in FIG. 2 maybe broadly considered to correspond with the core network 102represented in FIG. 1, and the respective controlling nodes 321, 322 andtheir associated distributed units/TRPs 311, 312 may be broadlyconsidered to provide functionality corresponding to base stations ofFIG. 1.

A terminal device 400 is represented in FIG. 2 within the coverage areaof the first communication cell 301. This terminal device 400 may thusexchange signalling with the first controlling node 321 in the firstcommunication cell via one of the distributed units 311 associated withthe first communication cell 301. For simplicity the present descriptionassumes communications for a given terminal device are routed throughone of the distributed units, but it will be appreciated in someimplementations communications associated with a given terminal devicemay be routed through more than one distributed unit, for example in asoft handover scenario and other scenarios. That is to say, referencesherein to communications being routed through one of the distributedunits should be interpreted as references to communications being routedthrough one or more of the distributed units. In this regard, theparticular distributed units through which a terminal device iscurrently connected through to the associated controlling node may bereferred to as active distributed units for the terminal device. Theactive subset of distributed units for a terminal device may compriseone or more than one distributed units (TRPs). The controlling node 321is responsible for determining which of the distributed units 311spanning the first communication cell 301 is responsible for radiocommunications with the terminal device 400 at any given time (i.e.which of the distributed units are currently active distributed unitsfor the terminal device). Typically this will be based on measurementsof radio channel conditions between the terminal device 400 andrespective ones of the distributed units 311. In this regard, it will beappreciated the subset of the distributed units in a cell which arecurrently active for a terminal device will depend, at least in part, onthe location of the terminal device within the cell (since thiscontributes significantly to the radio channel conditions that existbetween the terminal device and respective ones of the distributedunits).

In the example of FIG. 2, two communication cells 301, 302 and oneterminal device 400 are shown for simplicity, but it will of course beappreciated that in practice the system may comprise a larger number ofcommunication cells (each supported by a respective controlling node andplurality of distributed units) serving a larger number of terminaldevices.

It will further be appreciated that FIG. 2 represents merely one exampleof a proposed architecture for a new RAT telecommunications system inwhich approaches in accordance with the principles described herein maybe adopted, and the functionality disclosed herein for handlingmobility/handovers in a wireless telecommunications system may also beapplied in respect of wireless telecommunications systems havingdifferent architectures. That is to say, the specific wirelesstelecommunications architecture for a wireless telecommunications systemadapted to implement functionality in accordance with the principlesdescribed herein is not significant to the principles underlying thedescribed approaches.

The terminal device 400 comprises a transceiver unit 400A fortransmission and reception of wireless signals and a processor unit 400Bconfigured to control the terminal device 400. The processor unit 400Bmay comprise various sub-units for providing functionality in accordancewith embodiments of the present disclosure as explained further herein.These sub-units may be implemented as discrete hardware elements or asappropriately configured functions of the processor unit. Thus theprocessor unit 400B may comprise a processor unit which is suitablyconfigured/programmed to provide the desired functionality describedherein using conventional programming/configuration techniques forequipment in wireless telecommunications systems. The transceiver unit400A and the processor unit 400B are schematically shown in FIG. 2 asseparate elements for ease of representation. However, it will beappreciated that the functionality of these units can be provided invarious different ways, for example using a single suitably programmedgeneral purpose computer, or suitably configured application-specificintegrated circuit(s)/circuitry. It will be appreciated the terminaldevice 400 will in general comprise various other elements associatedwith its operating functionality, for example a power source, userinterface, and so forth, but these are not shown in FIG. 2 in theinterests of simplicity.

The first and second controlling nodes 321, 322 in this example arefunctionally identical but serve different geographical areas (cells301, 302). Each controlling node 321, 322 comprises a transceiver unit321A, 322A for transmission and reception of communications between therespective controlling nodes 321, 322 and distributed units 311, 312within their respective communication cells 301, 302 (thesecommunications may be wired or wireless). Each controlling node 321, 322further comprises a processor unit 321B, 322B configured to control thecontrolling node 321, 322 to operate in accordance with embodiments ofthe present disclosure as described herein. The respective processorunits 321B, 322B may again comprise various sub-units for providingfunctionality in accordance with embodiments of the present disclosureas explained herein. These sub-units may be implemented as discretehardware elements or as appropriately configured functions of theprocessor unit. Thus, the respective processor units 321B, 322B maycomprise a processor unit which is suitably configured/programmed toprovide the desired functionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. The respective transceiver units 321A, 322Aand processor units 321B, 322B for each controlling node 321, 322 areschematically shown in FIG. 2 as separate elements for ease ofrepresentation. However, it will be appreciated the functionality ofthese units can be provided in various different ways, for example usinga single suitably programmed general purpose computer, or suitablyconfigured application-specific integrated circuit(s)/circuitry. It willbe appreciated the controlling nodes 321, 322 will in general comprisevarious other elements, for example a power supply, associated withtheir operating functionality.

The respective distributed units (TRPs) 311, 312 in this example arefunctionally identical but serve different parts of their respectivecells. That is to say, the distributed units are spatially distributedthrough their respective communication cells to support communicationsfor terminal devices at different locations within the cells, asschematically indicated in FIG. 2. Each distributed unit 311, 312comprises a transceiver unit 1311A, 1312A for transmission and receptionof communications between the respective distributed units 311, 312 andtheir associated controlling node 321, 322 and also for transmission andreception of wireless radio communications between the respectivedistributed units 311, 312 and any terminal device they are currentlysupporting. Each distributed unit 311, 312 further comprises a processorunit 1311B, 1312B configured to control the operation of the distributedunit 311, 312 in accordance with the principles described herein. Therespective processor units 1311B, 1312B of the distributed units mayagain comprise various sub-units. These sub-units may be implemented asdiscrete hardware elements or as appropriately configured functions ofthe processor unit. Thus, the respective processor units 1311B, 1312Bmay comprise a processor unit which is suitably configured/programmed toprovide the desired functionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. The respective transceiver units 1311A,1312A and processor units 1311B, 1312B are schematically shown in FIG. 2as separate elements for ease of representation. However, it will beappreciated the functionality of these units can be provided in variousdifferent ways, for example using a single suitably programmed generalpurpose computer, or suitably configured application-specific integratedcircuit(s)/circuitry. It will be appreciated the distributed units 311,312 will in general comprise various other elements, for example a powersupply, associated with their operating functionality.

As discussed above, mobile communications networks such as network 100or network 300 may be used to carry transmissions for services with avariety of constraints, such as traffic which are high capacity and havesome tolerance to delay and traffic which is low capacity but with a lowtolerance to delay. While the principles of the disclosure will beillustrated in the context of a mobile network where a network element(e.g. TRP, eNB, BTS, . . . ) transmits eMBB and URLLC data to a mobileunit, it will be appreciated that the same principles apply to 3Gnetworks, LTE networks or any other suitable network and to anyappropriate type or types of data. Likewise, the same principles andteachings can also be used for uplink transmissions from a mobile deviceto a network receiver (e.g. BTS, eNB, TRP, etc.).

Returning to the example of eMBB and URLLC traffic, examples of suitablesubframe structures for sending eMBB data and URLLC data are illustratedin FIGS. 3 and 4 respectively. It is noteworthy that while the presentdisclosure is generally provided referring to subframes, the sameteachings apply in respect of frames or of any other suitable time unit.An example eMBB subframe structure is shown in FIG. 3 with transmissionperiod T_(eMBB) (e.g. 0.5 ms, 1 ms, 5 ms, 10 ms or 50 ms), where thecontrol channel uses significantly smaller transmission resources thanthat of the data channel. In this manner, the overhead caused by controltransmissions is reduced. On the other hand, if new URLLC data to besent is identified or received for transmission once the transmission ofan eMBB subframe has already started, it would have to be sent in afuture subframe which may lead to a delay in transmitting this data.Namely, the delay would be of at least the remaining transmission timefor the current eMBB subframe which may create a delay that is notacceptable to the URLLC transmission. Presented differently, as atrade-off for the lower overhead, the transmission delay for longersubframes is increased compared to the transmission delay for shortersubframes. This example eMBB subframe is thus well adapted to thetransmission of relatively high capacity and high delay tolerancetraffic (e.g. streaming of video, web traffic, etc.).

Now turning to FIG. 4, an example of a URLLC subframe structure isillustrated with a transmission period of T_(URLLC) (e.g. 0.25 ms),where the control and data channels occupy a short duration of timecompared to the subframe illustrated in FIG. 3. The transmission lengthof URLLC data T_(URLLC) is expected to be much smaller than that of eMBBT_(eMBB), that is, T_(eMBB)>>T_(URLLC). An example requirement currentlyconsidered for URLLC is a low latency transmission measured from theingress of a layer 2 packet to its egress from the network, with aproposed target of 1 ms. With such a subframe structure and compared tothat of FIG. 3, the overhead created by the transmission of controlinformation is greater but if new data is received during thetransmission of a current subframe, a new subframe can be sent quicker(as the transmission of the current subframe will finish earlier thanfor a longer subframe) and thus the delay for sending data is relativelysmaller. As the skilled person will appreciate, this type of subframe isbetter adapted for sending low capacity traffic that is sensitive todelay (e.g. emergency and safety systems, health monitoring, etc.), inaccordance with the expected low delay requirements for URLLC traffic,than for sending high capacity and high delay-tolerant traffic.

In a mobile network, it is generally expected that the differentservices can be multiplexed in the same system bandwidth. That wouldmean that eMBB and URLLC traffic would be scheduled by the network inthe same (time and/or frequency) resources and that the mobile unitreceiving the transmissions should be able to find the relevant types oftransmissions addressed to it. Possible options for multiplexing thesedifferent types of traffic and subframes include:

-   -   Orthogonal time resources multiplexing. Here the base station        uses a scheduling interval that is short enough to meet URLLC        latency requirements for both the eMBB and URLLC to allow URLLC        and eMBB to be scheduled on orthogonal transmission resources.        One disadvantage of this approach is that it creates a        relatively large amount of scheduling-related overhead for the        eMBB thereby significantly reducing its spectral efficiency.        Another option would be to reserve some time periods for URLLC        transmissions. One disadvantage would be that the amount of        reserved resources would have to be overestimated to try to        ensure that resources are always available for URLLC        transmissions (with a view to meeting the delay targets) which        is likely to result in a sub-optimal use of available resources        and thus a loss of capacity for the network (which in turn would        translate into a loss of capacity for eMBB traffic as well).    -   Orthogonal frequency resources, where eMBB and URLLC use        different frequency resources. One drawback is that, as when        reserving time resources for URLLC (see above), this is likely        to result in a reduced overall capacity for the network. Also,        in some systems, such as NR or 5G systems, orthogonal frequency        resource may not be available because the network can sometimes        be expected to serve many users and to occupy a large portion of        resources for eMBB transmissions for a relatively long time.

With a view to providing multiplexing of URLLC and eMBB transmissions ina manner that aims at providing a low latency URLLC transmission,another option is to occupy a subset of resources already allocated toeMBB for sending URLLC data. This is illustrated with reference to FIG.5, where an eMBB transmission started at time τ0, and is expected tooccupy all available transmission resources until time τ3. At time (orshortly before) τ1, a URLLC packet arrives and it needs to betransmitted immediately. If there are no other available transmissionresources, it can then occupy a portion of the eMBB resources as shownin FIG. 5 until time τ2. Different methods for multiplexing the twotypes of transmissions using resources originally allocated for one ofthe transmissions only include:

-   -   Superposing: The base station schedules the eMBB in the most        efficient way, for example with long scheduling intervals as        discussed with respect to FIG. 3. Then when a URLLC transport        block arrives, this is superposed (for example by use of        multi-user superposition) on the eMBB transmission. This means        that the eMBB transmission would then suffer from some        multi-user superposition interference on those resource elements        shared with the URLLC transport blocks. This can result        potentially in both the eMBB and the URLLC transmissions being        corrupted.    -   Puncturing: The eNodeB schedules the eMBB in the most efficient        way, for example with long scheduling intervals as above. Then        the eNodeB punctures the eMBB transmission to create space to        fit the arriving URLLC transport block. This means that some of        the transmission resources previously designated for use by the        eMBB transport blocks are allowed to be used for transmitting        URLLC transport blocks instead. The eMBB samples that were        designated to be transmitted on the punctured transmission        resources are not transmitted at all and are effectively removed        from the transmission.

Superposing or puncturing an eMBB transmission as discussed above wouldaffect the likelihood of the eMBB transmission being safely received orrecovered and this may lead to a failed transmission. Some possiblemethods to ensure recovery of the eMBB transport block (TB) include:

-   -   Use of an existing HARQ retransmission scheme (or similar) for        the data of the eMBB packet to be retransmitted when the data        was too corrupted to be recovered. However unlike other        transmissions (e.g. legacy LTE packet transmission), eMBB        transmissions can be resource intensive and the retransmission        would occupy a large portion of the available resources. This        would result in a large number of resources being required for        retransmitting the corrupted data (which may be much larger than        the resources used for the URLLC transmission).    -   Use outer layer coding, where additional coding is performed on        multiple eMBB packets. However this would introduce high latency        in receiving the eMBB packets since the UE needs to receive        several eMBB packets and the outer layer coding parity bits in        order to perform the outer layer decoding process and since the        eMBB subframes for sending EMBB packets are expected to be        relatively long.

It will thus be appreciated that in these cases, the collision betweenthe eMBB data and the URLLC data is such that this may not besatisfactorily addressed and that the eMBB transmission may not beeasily recovered without causing further problems.

Therefore, in the event that a first (e.g. eMBB) transmission has beenaffected by a second (e.g. URLLC) transmission, the eMBB transmission isless likely to be decoded by the terminal. Some safeguardingarrangements may be used with a view to reducing the likelihood of aterminal failing to decode the first transmissions: see for example EPapplication EP16189083.5 filed 15 Sep. 2016, the content of which isfully incorporated herein by reference. It is however expected that evenwith such safeguards in place, and even more so if no such safeguardsare used, at least in some cases the terminal will not be able tosuccessfully decode the first transmission. Current systems can enablethe terminal to request retransmission of corrupted data, however such aretransmission would use a large amount of resources as the entire eMBBdata would have to be retransmitted.

According to the present disclosure, there is provided an arrangementwhere the efficiency of the retransmissions can be improved, therebyreducing the amount of resources used for repairing a transmissionaffected by the transmission of another transmission in its allocatedresources.

In one example, there is provided an arrangement wherein an indicationis received that a terminal has been unable to decode first data (e.g.eMBB data) from a set of identified resources allocated to the terminalfor the transmission of the first data; upon receipt of the indication,it is identified that a portion of the identified resources has beenused to transfer data other than the first data (e.g. URLLC data); and asubset of the first data is retransmitted, the subset of the first datacomprising the portion of the first data that was previously transmittedin the portion of the identified resources. Accordingly, some but notall of the first data can be retransmitted as the source of the datacorruption can be identified and thus the corrupted portion can therebybe identified. In turn, this can provide a valuable resources saving,especially in cases where, in the time unit (e.g. frame, subframe, etc.)in question, the resources corrupted by the second transmission arerelatively small compared to the total amount of resources allocated tothe first transmission as the amount of retransmitted data can therebybe potentially significantly reduced.

More specific example implementations of the present disclosures willnow be described, wherein the invention is not limited by the specificexamples provided herein but only by the appended claims. For example,while the examples provided herein generally involve an eMBBtransmission that has been affected by a puncturing or by superimposedURLLC transmissions, the teachings of the present disclosure are notlimited to eMBB and/or URLLC transmissions and these exampletransmissions are used for illustrative purposes only.

In most of the current mobile networks, the retransmission mechanismimplemented is the Hybrid Automatic Repeat reQuest (aka “Hybrid ARQ” or“HARQ”) and, as mentioned above, using HARQ is one method available forrepairing eMBB transmissions that have been corrupted (punctured orsuperposed) by URLLC. However, the HARQ retransmission is resourceintensive since in a HARQ retransmission, a whole subframe needs to bere-transmitted. On the other hand, the URLLC corruption may have onlycovered a few resource elements that was constrained in both the timeand frequency domains within the resources originally allocated for theeMBB transmission. An example of a conventional repair of an eMBBtransmission using HARQ is illustrated in FIG. 6. In a first subframe aneMBB transmission 610 is scheduled by a PDCCH 600. The eMBB transmission620 is then corrupted by an urgent URLLC transmission 620 in the samesubframe. The low delay tolerance of the URLLC transmission 620 causedthe transmission of the URLLC data in resources that were allocated forthe eMBB transmission 610 (e.g. rather than waiting for the nextsubframe for resources to be allocated in a conventional PDCCH andspecifically for the URLLC transmission). In turn, this causes thedecoding of the eMBB transmission to be unsuccessful and the UE to senda NACK feedback to the eNodeB. As per the HARQ procedure, the NACKfeedback triggers a retransmission and the eNodeB schedules a HARQre-transmission of the eMBB transmission in a later subframe labelled inthe figure. The same eMBB data 610 is sent again, using resourcesallocated in PDCCH 601 for the later subframe. The retransmissionincludes both the non-corrupted data (that is in the resources for 610not used by transmission 620) and the corrupted data (that is in theresources used by transmission 620).

In accordance with the present disclosure, in cases where a URLLCtransmission collides with an eMBB transmission, the amount ofretransmitted eMBB bits from the bits that did not collide with theURLLC transmission can be reduced, thereby improving the efficiency ofthe network and in particular a more efficient method of re-transmission(HARQ or otherwise) for cases where there are collisions between twotransmissions, one being scheduled in a controlled channel for a timeunit (e.g. eMBB transmission) and another one being transmitted despitenot being scheduled in the control channel for the time unit in which itis transmitted (e.g. URLLC transmission for another UE).

In an example of the present disclosure, the retransmitted datacorresponds to exactly the corrupted portion of the eMBB transmission,as illustrated with reference to FIG. 7. In this example, where possiblyonly the eMBB physical bits, or alternatively only the QAM symbols, thatwere corrupted by the URLLC transmission are re-transmitted. Thenumbering in FIG. 7 corresponds to that of FIG. 6 but where theretransmitted data 711 corresponds in time and frequency to the portion(e.g. data bit or QAM symbol portion) of eMBB transmission 710 affectedby the URLLC transmission 720. This figure shows that in this examplethe HARQ re-transmission consists of exactly the modulation symbols(mapped from physical bits) that were corrupted in the previoustransmission 710. Although in FIG. 7 the retransmitted data 711 is shownin the same time and frequency resources within the subframe as theURLLC transmission causing the corruption, in other implementations inaccordance with this example the retransmission 711 will have the sameshape and amount of time and frequency resources as the transmission 720but the retransmission can use different time and/or frequency resourceswithin the subframe for the retransmission.

It is noteworthy that, in some cases it may not be appropriate for there-transmission to be based on the physical bits that were corrupted,but it may be more appropriate to base the retransmission instead on theQAM symbols (also sometimes referred to as modulation symbols) that werecorrupted. This may be especially relevant in cases where there is someinterdependency between the QAM symbols. Such interdependency exists,for example, in the following modulation schemes: differentialmodulation, multi-dimensional modulation and signal space diversity. Insuch cases, the QAM symbols that were corrupted can be re-transmittedrather than the physical bits.

The example illustrated in FIG. 7 shows a retransmission occupyingexactly the same physical resources (only in a different subframe) asthe physical resources that were corrupted in a previous subframe.Carrying out the retransmission on exactly the same physical resourcescan be useful since it facilitates the repairing of the firsttransmission by the terminal. In particular, a UE may implement a“symbol combining” architecture wherein the UE can simply replace thetransmission received in the resources for 720 by the retransmission 711and attempt to decode the transmission 710 based on this re-combinedtransmission. However, in some cases it may not be possible to allocateresources for the re-transmission 711 in the later subframe that canreplicate the shape of the URLLC transmission 720. For example, in somemobile systems, a standard allocation of resources in a PDCCH may onlytake the shape of resources from the end of the control channel untilthe end of the subframe. In this case it may not be possible to allocateresources that have the same time and frequency dimensions as thecolliding URLLC transmission.

Accordingly, in one example the shape of the re-transmitted resourcescan be different to the shape of the resources corrupted by the URLLCtransmission. For example, the re-transmitted resources could occupyfewer subcarriers over a larger number of OFDM symbols. In such animplementation, these resources could assist with multiplexing this typeof retransmission with other eMBB transmissions. An example of such aretransmission is illustrated in FIG. 8. Again, the numbering in FIG. 8corresponds to that of FIGS. 6 and 7. The retransmission uses differentresources 811 within the subframe (compared to the resources used bytransmission 820) and the resources contain the same number of resourceelements as the resources that were corrupted in the first subframe, inaccordance with this first example implementation.

In another example, as illustrated in FIG. 9 an eMBB retransmission 911uses, in a different subframe, the same physical resources as thecorrupting URLLC transmission 920. At the time of scheduling the eMBBre-transmission, the eNodeB may not know whether there will be futureurgent URLLC transmissions, but it can reserve the subcarrier rangeoccupied by the eMBB re-transmission 911, in OFDM symbols not used bythe eMBB re-transmission, for use by future potential URLLCtransmissions. As illustrated in FIG. 9, the eMBB re-transmission uses asubcarrier range over the OFDM symbols occupied by the eMBBretransmission 911 and these subcarriers are unused by the eMBBre-transmission in OFDM symbols before and after the eMBB retransmission911. These subcarriers and OFDM symbols cannot be assigned to other eMBBtransmissions (e.g. because the shape of the available physical resourcemay not be compatible with the eMBB allocation signalling). Theseresources are instead blocked out for potential use by future URLLCtransmissions. If at a future point in time, a URLLC has to betransmitted urgently, the URLLC scheduler can preferentially schedulethe urgent URLLC transmission using these blocked out resources, ratherthan puncture a previously scheduled eMBB transmission for example.

In yet another example, eMBB resources 1031 can be allocated that are ofa shape containing a gap, wherein the gap is the size of a URLLCtransmission, as illustrated in FIG. 10. The resource allocationsignalling currently used in mobile networks does not enable such a typeof resource allocation with a gap but another type of resourceallocation signalling could easily define a set of resource elementscontaining a gap. Within a rectangular block of resource elements 1041,the eNodeB can thus schedule:

-   -   An eMBB re-transmission to UE1 in resources 1011; and    -   An eMBB transmission using resource elements containing a gap to        UE2 in resources 1031

In the example of FIG. 10 the gap for resources 1011 is of the sameshape as the URLLC transmission resources 1020 when the collisionoccurred but in other examples, the gap may be of a different shape (seefor example the discussion above in respect of FIG. 8). Also, while thegap 1011 has been represented being in the middle of the block 1041 inthe example of FIG. 10, this is not a requirement in accordance with thepresent disclosure and in other examples it may for example be at one,two or three edges of the block 1041.

Some of the above example implementations may not allow a symbolcombining method to be used, as discussed above, since the ResourceElement (RE) locations of the symbols have been moved compared to thatof the corrupted REs. This situation can however be addressed byincluding an RE demapper prior to performing symbol combining. Theoperation of the demapper is schematically represented in FIG. 11. Inbrief, the demapper enables the terminal to rearrange the retransmittedresources 1111 to resources 1111′ corresponding to the eMBB resourceslost with the URLCC collision. The terminal can in some examples beconfigured to always re-arrange the symbols using the same method (e.g.by defining an order for the symbols, e.g. increasing time thenfrequency, the other way around or any other suitable order) or thedemapping parameters can be indicated to the terminal, for example inthe control channel used to schedule the retransmission.

In another example of the present invention, the amount of resource thatis re-transmitted can be larger than the amount of resources directlyaffected by the URLLC collision. For example, it may depend onsignalling from the terminal, as will be clear from the discussionbelow.

In some cases, the URLLC transmission can be transmitted with adifferent set of reference signals (“RS”) to the eMBB transmission. Inthese cases, the channel estimation used to decode the eMBB transmissionmay also have been corrupted by the colliding URLLC transmission suchthat simply retransmitting the corrupted symbols or bits may not besufficient to repair the eMBB transmission. As the channel estimationalgorithm typically averages its channel estimation across subcarriers(in the frequency dimension) and/or OFDM symbols (in the timedimension), the corruption from the URLLC transmission may impact alarger number of resource elements in the receiver than in thetransmitter. In other words, the receiving and/or decoding of the REs inthe vicinity of the collision area may also be affected even though theREs themselves may not have been changed as a result of the collisionbetween the eMBB and URLLC transmissions. The channel estimationalgorithm employed is down to UE implementation and different terminalsmay average channel estimates across different amounts of resource inone or two dimensions. The type of channel estimation used by theterminal is expected to affect a desired amount of retransmission in acase where reference signals have been affected by the collision but theeNodeB carrying out the retransmission may not be aware of whichspecific type of channel estimation the terminal is using.

Accordingly, in one implementation, the UE can indicate to the eNodeBhow large or how much larger (compared to the collision area) the eMBBre-transmissions can be with a view to increasing the likelihood of asuccessful repair. The following signalling may be used by the terminalfor providing such an indication:

-   -   In the UCI (reporting ACK/NACK), a field can indicate how many        “extra resource elements surrounding the URLLC collision” need        to be re-transmitted. This can be used as a dynamic form of        signalling.    -   In RRC signalling (e.g. at connection setup), the UE can        indicate to the eNodeB how many “extra resource elements        surrounding the URLLC collision” need to be included in a        re-transmission whenever a URLLC transmission collides with an        eMBB transmission. This can be used as a semi-static form of        signalling. Alternatively, the UE can indicate “type” or        “category” information that the eNodeB can use to determine how        many extra resource elements surrounding a URLLC collision are        required for repair. For example, the UE can indicate that it is        a “type” of UE that averages channel estimates across 12        subcarriers. In that case, the eNodeB could decide, for this UE        (and other UEs of the same type), to oversize eMBB        retransmissions by 12 subcarriers around the edges of the eMBB        data that was corrupted and that is being prepared for        retransmission.

FIG. 12 illustrates a retransmission in accordance with this exampleimplementation. In this example, it is assumed that the terminal haspreviously indicated to the eNodeB that it is averaging RS in thefrequency dimension with an indication of the extent of the averaging orthat, when an eMBB repair occurs, N_(CE) extra resource elements need tobe transmitted above any corrupted eMBB portion and N_(CE) extraresource elements need to be transmitted below any corrupted eMBBportion. As mentioned above, this can be indicated to the eNodeB viasemi-static RRC configuration signalling. The figure shows that the eMBBrepair transmission 1211 consists of:

-   -   a set of REs 1211 b that match the REs that were collided with        by URLLC in transmission 1220    -   N_(CE) REs 1211 a above the retransmitted REs that were        corrupted by URLLC collision.    -   N_(CE) REs 1211 c below the retransmitted REs that were        corrupted by URLLC collision.

The terminal can use the extra sets of N_(CE) REs in order to improvethe channel estimates for the retransmitted REs that were corrupted byURLLC collision sent in 1211 b in the example of FIG. 12. It can alsouse these additional REs for HARQ recombination of these surroundingN_(CE) REs as these might also have been affected by the different RSsent in the transmission 1220 and may thus also be repaired with theretransmission.

While in this example the additional REs used in the retransmission havebeen added on either side-in the frequency dimension-of the resourcesused for retransmitting the REs that were used for the URLLCtransmission, in other examples they may only be added on either side inthe time dimension while in yet further examples they may be added oneither side in the time and frequency dimensions. Examples of additionalREs used when retransmitting the eMBB transmission have been included inFIG. 13, although the examples of FIG. 13 do not provide an exhaustivelist of all possible examples for including additional REs in accordancewith the teachings of the present disclosure.

Regardless of the desire to send additional REs when the terminal'schannel estimation might have been affected, there may be other caseswhere more eMBB REs might be transmitted than just the ones that wereinstead used by the URLCC transmissions.

For example, it may not always be possible to signal to an eMBB UE theallocation for just the eMBB portion that was used by the URLLCtransmission as illustrated in FIG. 7. The resource signalling (forexample in the DCI) may itself have limited capacity such that it maynot be possible to signal every possible amount of retransmissionphysical resource to the UE.

Now looking at the example of FIG. 8, the allocation shown there mightresult in a close number of resources elements compared to that for thecorrupted resource, however it may not be exactly identical. Forexample, a URLLC transmission may consist of 7 OFDM symbols and a numberof subcarriers, n_(SC_URLLC), whereas an eMBB transmission may consistof 26 OFDM symbols and a number of subcarriers, n_(SC_MBB) (where asubframe may consist of 28 OFDM symbols, of which 2 are reserved forcontrol channels). If, for example, the URLLC transmission consisted of10 subcarriers (a total of 70 resource elements when 7 OFDM symbols areused), the eMBB HARQ repair transmission could consist of 26*2=52resource elements or 26*3=78 resource elements.

Accordingly, it is proposed that the HARQ re-transmission can in someexamples be a rate matched version of the physical bits that werecorrupted by the URLLC transmission. The rate matching may occur onphysical bits or on QAM symbols (as will be clear from the discussionbelow) as for some modulation schemes, it may be desirable tore-transmit modulation symbols rather than physical bits (as previouslymentioned).

If more REs than the number of corrupted REs (including extra REs forchannel estimation or not), have to be used in the retransmission, forexample because of limitations in the resource allocation signalling,this can be used to increase the reliability of the retransmission.Also, in some circumstances it will be desired that the “eMBB repair”transmission should be more robust than the resources that werecorrupted by the URLLC transmission and more resources can then beallocated to improve the reliability. For example, if the Log-LikelihoodRatios (“LLRs”) from the URLLC transmission were added onto a previouseMBB transmission, the LLRs in the “corrupted region” become lessreliable than before the corruption and in this case, it may bebeneficial to re-transmit the corrupted region with extra reliability(in order to overcome the corruption). In some embodiments, thereception of the eMBB re-transmission will cause the terminal to deletesoft channel bits in the region that was corrupted by the URLLCtransmission and it may be beneficial if this “eMBB repair” transmissionhas increased robustness to ensure a safe decoding of the entire eMBBtransmission. For example, if the HARQ buffer had previously received 2HARQ re-transmissions before having a third HARQ re-transmission beingcorrupted by the URLLC transmission, the “eMBB repair” transmissioncould be transmitted with three times the amount of resource of theinitial HARQ transmission. In other words, the repair re-transmissionwould correspond to twice the amounts of resource relating to the 2 HARQre-transmissions that were deleted and one time the amount of resourcerelating to the soft channel bits that were not received due to theURLLC transmission. In such cases, increased REs can be used to increasethe robustness of the repair retransmission.

Whether more resources than just the directly corrupted resources arebeing used by choice and/or by design, the same principles will apply asthe skilled person will recognise.

FIG. 14 illustrates an example of how a more robust “eMBB repair”re-transmission can be generated through rate matching of physical bits.In this example, a set of 800 physical bits (400 modulation symbols) istransmitted for the eMBB transmission and 100 physical bits (50modulation symbols) of this transmission are corrupted by a URLLCtransmission. In the example of FIG. 14:

-   -   The initial transmission is rate matched to create a set of        physical bits a₀ . . . a₇₉₉    -   These physical bits are further processed to create a set of        resource elements b₀ to b₃₉₉. The further processing may consist        of various operations, including mapping to modulation symbols        (in this example, QPSK modulation is envisaged)    -   The portion of resource elements b100 to b149 were intended to        be mapped to a portion of resource that is corrupted by a URLLC        transmission, either through puncturing (replacement) or        superposition for example.    -   For the HARQ re-transmission (the “eMBB repair” transmission),        the physical bits a₂₀₀ . . . a₂₉₉ (corresponding to the resource        elements that were corrupted by URLLC) are further rate matched,        by a block labelled “rate match 2”. In this example, these bits        are repeated two times to create a physical bit stream a′₂₀₀ . .        . a′₃₉₉.    -   The physical bits stream a′₂₀₀ . . . a′₃₉₉ is further processed        to produce a set of resource elements b′₁₀₀ . . . b′₁₉₉.

According to this example, for the same portion of data, twice as manyresource elements are used for the retransmission compared to the numberof resource elements allocated for the original transmission (b₁₀₀ . . .b₁₄₉). As a result, this re-transmission is more robust than the initialtransmission. Although the example of FIG. 14 shows a retransmissionwhich is similar to the type described with reference to FIG. 8, theskilled person will appreciate that this aspect is merely illustrativeand any other type of shape of retransmission may be used as appropriate(the same comment also applies to FIG. 15 discussed below).

The example discussed with respect to FIG. 14 can be generalised in theexample illustrated in FIG. 15 considered with the following parametertable:

Parameter meaning n_(pb) Number of physical bits in the initialtransmission n_(ms) Number of modulation symbols in the initialtransmission i_(ms) _(—) _(URLLC1) Index of first modulation symbolcorrupted by URLLC i_(ms) _(—) _(URLLC2) Index of last modulation symbolcorrupted by URLLC l_(pb) _(—) _(URLLC1) Index of first physical bitcorrupted by URLLC l_(pb) _(—) _(URLLC2) Index of last physical bitcorrupted by URLLC i_(ms) _(—) _(repair1) Index of first modulationsymbol in eMBB repair transmission i_(ms) _(—) _(repair2) Index of lastmodulation symbol in eMBB repair transmission l_(pb) _(—) _(repair1)Index of first physical bit in eMBB repair transmission l_(pb) _(—)_(repair2) Index of last physical bit in eMBB repair transmission

The skilled person will appreciate that the principles discussed inrespect of FIG. 14 apply equally here such that, in this example:

-   -   The initial transmission is rate matched to create a set of        physical bits a₀ . . . a_(npb)    -   These physical bits are further processed to create a set of        resource elements b₀ to b_(nms). The further processing may        consist of various operations, including mapping to modulation        symbols (in this example, QPSK modulation is envisaged)    -   The portion of resource elements b_(ims_URLLC1) . . .        b_(ims_URLLC2) were intended to be mapped to a portion of        resource that is corrupted by a URLLC transmission    -   For the HARQ re-transmission (the “eMBB repair” transmission),        the physical bits a_(ipb_URLLC1) a_(ipb_URLLC2) (corresponding        to the resource elements that were corrupted by URLLC) are        further rate matched, by a block labelled “rate match 2”. In        this example, these bits are repeated two times to create a        physical bit stream a′_(ipb_repair1) . . . a′_(ipb_repair2).    -   The physical bits stream a′_(ipb_repair1) . . . a′_(ipb_repair2)        is further processed to produce a set of resource elements        b′_(ims_repair1) . . . b′_(ims_repair2). Note that there are        twice as many resource elements here as for the initial        transmission (b_(ims_URLLC1) . . . b_(ims_URLLC2)), hence this        re-transmission is more robust than the initial transmission.

Accordingly, the physical bits of the eMBB transmission can berate-matched differently when retransmitted with a view to improving thereliability of the retransmission. It is noteworthy that theserate-matching adaptation techniques may be used regardless of whetherthe retransmitted bits correspond exactly to that affected by the URLCCtransmission (i.e. that in the resources allocated for the eMBBtransmission but used for the URLLC transmission) or include additionalresources (e.g. to correct channel estimation errors also caused by theURLLC collision).

While this previous example is directed to the rate matching of physicalbits when generating the HARQ re-transmissions for the eMBB repair, inanother example modulation symbols may be rate matched when generatingHARQ re-transmissions for the eMBB repair. As for the physical bits ratematching example, these techniques may be used whether exactly thecorrupted symbols are re-transmitted (or symbols corresponding to thecorrupted symbols are re-transmitted) or whether additional symbols arealso transmitted.

This further example is illustrated with reference to FIG. 16 where aset of 800 physical bits (400 modulation symbols) is part of theoriginal eMBB transmission wherein 100 physical bits (50 modulationsymbols) of these are corrupted by a URLLC transmission. As for FIGS. 14and 15, the skilled person can generalise this example to other lengthsof eMBB bit streams and corrupting bit streams and to other rates forthe rate matching. Returning to FIG. 16:

-   -   The initial transmission is rate matched to create a set of        physical bits a₀ . . . a₇₉₉    -   These physical bits are further processed to create a set of        resource elements b₀ to b₃₉₉. The further processing may consist        of various operations, including mapping to modulation symbols        (in this example, QPSK modulation is envisaged)    -   The portion of resource elements b₁₀₀ to b₁₄₉ were intended to        be mapped to a portion of resource that is corrupted by a URLLC        transmission    -   For the HARQ re-transmission (the “eMBB repair” transmission),        the modulation symbols b₁₀₀ to b₁₄₉ (corresponding to the        resource elements that were corrupted by URLLC) are further rate        matched, by a block labelled “rate match 2”. In this example,        these modulation symbols are repeated twice to create a        modulation symbol stream b′₁₀₀ . . . b′₁₉₉.

In this example, there are twice as many resource elements for theretransmission compared to the number of REs for the originaltransmission (b₁₀₀ . . . b₁₄₉) for the same portion of the eMBB data. Asa result the robustness of the eMBB transmission has been improved inthis re-transmission.

While conventionally the retransmissions are triggered by thetransmission of a NACK message from a terminal, in accordance with oneexample of the present disclosure, the retransmission procedures can besped up by automatically retransmitting the corrupted originaltransmission, regardless of whether the recipients (terminals) wereactually able to decode and repair the corrupted transmission on theirown.

It is noteworthy that in a conventional HARQ arrangement, a typical HARQround trip time is generally of 8 subframes so that the UE is allowedtime to decode the PDSCH, to generate an ACK/NACK, so that the eNodeB anreceive and decode the ACK/NACK and schedule a HARQ re-transmission. Inaccordance with the present technique, the eNodeB may identify an eMBBtransmission that has been corrupted by a URLLC transmission. Such aneMBB transmission is likely to cause a UE to send a NACK to the eNodeBand the HARQ round trip time can be shortened with the eNodeB sending an“eMBB repair” HARQ re-transmission straight after or shortly aftersending the initial transmission. In this case the eNodeB can send thepartial retransmission before any NACK is received (and as the skilledperson will appreciate, potentially no NACK messages will in fact besent). The reception of this “eMBB repair” transmission by the UE can beused in different ways.

-   -   The terminal may only make use of this re-transmission if it is        unable to decode the first transmission, for example instead of        sending a NACK message back the terminal it can use the        re-transmission straightaway.    -   This re-transmission can trigger the UE to abort transport        channel decoding of the corrupted transmission and to:        -   start physical channel processing of the “eMBB repair”            transmission instead; and        -   then start transport channel processing of the combined            initial transmission and eMBB repair transmission

Accordingly, in accordance with the present disclosure retransmissiontechniques can be provided for assisting with the repair of thecorruption of a first transmission by an urgent transmission usingresources originally allocated for the first transmission, wherein thetechniques can assist with a more efficient use of the network'sresources and potentially with a quicker repair as well.

While the discussions above have generally been presented in the contextof transmissions to one terminal being punctured however, as the skilledperson will appreciate, the same principles apply if the transmissionsto two or more terminals are being punctured. For example, the URLLCtransmission may use some resources originally allocated for a datatransmission to a first terminal or group of terminals as well as otherresources originally allocated for a data transmission to a secondterminal or group of terminals. In effect, it is not relevant to therecipient(s) of a punctured transmission that other transmissions mighthave been punctured as well, what is relevant to the recipient is whichof its resources have been used to send other data instead of its dataor superimposed with its data. The principles herein can thus be appliedequally to puncturing/superposition of transmissions to differentrecipients.

As the skilled person will appreciate, the terms terminal, UE, mobiledevice, mobile terminal, etc. can be used interchangeably and are notintended to be limiting. Likewise, the term base station has generallybeen used and is intended to include at least BTS, eNB, eNodeB, TRP,etc.

While the invention has generally been discussed in the context ofdownlink transmissions, it will be appreciated that the same principlesmay be used for uplink transmissions.

Thus there has been described a retransmission method for use in atelecommunications system, the method comprising: transmitting, to aterminal, first data in a set of identified resources allocated for thetransmission of the first data; identifying that a portion of theidentified resources has been used to transmit data other than the firstdata; and retransmitting a subset of the first data, the subset of thefirst data comprising the portion of the first data that was previouslyscheduled to be transmitted in the portion of the identified resources.

Further particular and preferred aspects of the present invention areset out in the accompanying independent and dependent claims. It will beappreciated that features of the dependent claims may be combined withfeatures of the independent claims in combinations other than thoseexplicitly set out in the claims.

Thus, the foregoing discussion discloses and describes merelyillustrative embodiments of the present invention. As will be understoodby those skilled in the art, the present invention may be embodied inother specific forms without departing from the spirit or essentialcharacteristics thereof. Accordingly, the disclosure of the presentinvention is intended to be illustrative, but not limiting of the scopeof the invention, as well as other claims. The disclosure, including anyreadily discernible variants of the teachings herein, define, in part,the scope of the foregoing claim terminology such that no inventivesubject matter is dedicated to the public.

In the present disclosure, method steps discussed herein may be carriedout in any suitable order and not necessarily in the order in which theyare listed. For example, steps may be carried out in an order whichdiffers from an order used in the examples discussed above or from anindicative order used anywhere else for listing steps (e.g. in theclaims), whenever possible or appropriate. Thus, in some cases, somesteps may be carried out in a different order, or simultaneously(entirely or in part) or in the same order. So long as an order forcarrying any of the steps of any method discussed herein is technicallyfeasible, it is explicitly encompassed within the present disclosure.

As used herein, transmitting information or a message to an element mayinvolve sending one or more messages to the element and may involvesending part of the information separately from the rest of theinformation. The number of “messages” involved may also vary dependingon the layer or granularity considered. For example transmitting amessage may involve using several resource elements in an LTEenvironment such that several signals at a lower layer correspond to asingle message at a higher layer. Also, transmissions from one terminalto another may relate to the transmission of any one or more of userdata, discovery information, control signalling and any other type ofinformation to be transmitted.

Also, whenever an aspect is disclosed in respect of an apparatus orsystem, the teachings are also disclosed for the corresponding method.Likewise, whenever an aspect is disclosed in respect of a method, theteachings are also disclosed for any suitable corresponding apparatus orsystem. Additionally, it is also hereby explicitly disclosed that forany teachings relating to a method or a system where it has not beenclearly specified which element or elements are configured to carry outa function or a step, any suitable element or elements that can carryout the function can be configured to carry out this function or step.For example any one or more of a mobile terminal, a base station or anyother mobile unit may be configured accordingly if appropriate, so longas it is technically feasible and not explicitly excluded.

Whenever the expressions “greater than” or “smaller than” or equivalentare used herein, it is intended that they discloses both alternatives“and equal to” and “and not equal to” unless one alternative isexpressly excluded or is not technically relevant.

It is noteworthy that even though the present disclosure has beendiscussed in the context of LTE and/or 5G, its teachings are applicableto but not limited to LTE, 5G or to other 3GPP standards. In particular,even though the terminology used herein is generally the same or similarto that of the 5G standards, the teachings are not limited to thepresent version of 5G and could apply equally to any appropriatearrangement not based on 5G and/or compliant with any other futureversion of an 5G or 3GPP or other standard.

Respective features of the present disclosure are defined by thefollowing numbered examples:

Example 1

A retransmission method for use in a mobile telecommunications system,the method comprising:

transmitting, to a terminal, first data in a set of identified resourcesallocated for the transmission of the first data;

identifying that a portion of the identified resources has been used totransmit data other than the first data; and

retransmitting a subset of the first data, the subset of the first datacomprising the portion of the first data that was previously scheduledto be transmitted in the portion of the identified resources.

Example 2

The method of Example 1 further comprising:

receiving an indication that the terminal has been unable to decode thefirst data from the set of identified resources;

wherein, optionally, the identifying step is carried out upon receipt ofthe indication.

Example 3

The method of Example 1 or 2 wherein, upon determination by the terminalthat the terminal is unable to decode the first data from the set ofidentified resources, the terminal attempts to decode the first datausing at least a part of the transmission received in the set ofidentified resources and using the retransmission of the subset of thefirst data.

Example 4

The method of any preceding Example wherein the portion of theidentified resources has been used to transfer either only the otherdata or both the other data and the first data.

Example 5

The method of any preceding Example wherein the subset of the first datacorresponds exactly to the portion of the first data.

Example 6

The method of any of Examples 1 to 4 wherein the subset of the firstdata comprises more than the portion of the first data.

Example 7

The method of any preceding Example wherein retransmitting the subset ofthe first data comprises transmitting or retransmitting the physicalbits that correspond to the physical bits that were scheduled to betransmitted in the set of identified resources for sending the subset ofthe first data.

Example 8

The method of any preceding Example wherein retransmitting the subset ofthe first data comprises transmitting or retransmitting the modulationsymbols for sending the subset of the first data in the set ofidentified resources.

Example 9

The method of any of Examples 1 to 7 wherein retransmitting the subsetof the first data comprises transmitting or retransmitting the subset ofthe first data using a retransmit rate matching procedure changing therobustness of the retransmission relative to the robustness provided bythe transmit rate matching procedure used for sending the first data.

Example 10

The method of Example 9 wherein the rate-matching procedure is at leastone of a physical bit rate matching procedure and a modulation symbolrate matching procedure.

Example 11

The method of any of Examples 1 to 7 wherein retransmitting the subsetof the first data comprises transmitting or retransmitting the subset ofthe first data using an amount of resources that is different than theamount of resources used for transmitting the subset of the first datain the set of identified resources.

Example 12

The method of any preceding Example wherein the set of identifiedresources is in a first time unit and wherein retransmitting a subset ofthe first data comprises retransmitting the subset of the first data ina further set of identified resources, the further set of identifiedresources being a second time unit subsequent to the first time unit.

Example 13

A base station for use in a mobile telecommunications system, the basestation being configured to:

transmit, to a terminal, first data in a set of identified resourcesallocated for the transmission of the first data;

identify that a portion of the identified resources has been used totransmit data other than the first data; and

retransmit a subset of the first data, the subset of the first datacomprising the portion of the first data that was previously scheduledto be transmitted in the portion of the identified resources.

Example 14

The base station of Example 13 further configured to:

receive an indication that the terminal has been unable to decode thefirst data from the set of identified resources;

wherein, optionally, the base station is also configured to identifythat a portion of the identified resources has been used to transmitdata other than the first data upon receipt of the indication.

Example 15

The base station of any one of Examples 13 to 14 wherein, upondetermination by the terminal that the terminal is unable to decode thefirst data from the set of identified resources, the terminal attemptsto decode the first data using at least a part of the transmissionreceived in the set of identified resources and using the retransmissionof the subset of the first data.

Example 16

The base station of any one of Examples 13 to 15 wherein the portion ofthe identified resources has been used to transfer either only the otherdata or both the other data and the first data.

Example 17

The base station of any one of Examples 13 to 16 wherein the subset ofthe first data corresponds exactly to the portion of the first data.

Example 18

The base station of any one of Examples 13 to 16 wherein the subset ofthe first data comprises more than the portion of the first data.

Example 19

The base station of any one of Examples 13 to 18 wherein retransmittingthe subset of the first data comprises transmitting or retransmittingthe physical bits that correspond to the physical bits that werescheduled to be transmitted in the set of identified resources forsending the subset of the first data.

Example 20

The base station of any one of Examples 13 to 19 wherein retransmittingthe subset of the first data comprises transmitting or retransmittingthe modulation symbols for sending the subset of the first data in theset of identified resources.

Example 21

The method of any one of Examples 13 to 19 wherein retransmitting thesubset of the first data comprises transmitting or retransmitting thesubset of the first data using a retransmit rate matching procedurechanging the robustness of the retransmission relative to the robustnessprovided by the transmit rate matching procedure used for sending thefirst data.

Example 22

The method of Example 21 wherein the rate-matching procedure is at leastone of a physical bit rate matching procedure and a modulation symbolrate matching procedure.

Example 23

The base station of any one of Examples 13 to 19 wherein retransmittingthe subset of the first data comprises transmitting or retransmittingthe subset of the first data using an amount of resources that isdifferent than the amount of resources used for transmitting the subsetof the first data in the set of identified resources.

Example 24

The base station of any one of Examples 13 to 23 wherein the set ofidentified resources is in a first time unit and wherein retransmittinga subset of the first data comprises retransmitting the subset of thefirst data in a further set of identified resources, the further set ofidentified resources being a second time unit subsequent to the firsttime unit.

Example 25

A base station for use in a mobile telecommunications system, the basestation being configured to carry out the method of any one of Examples1 to 12.

Example 26

Circuitry for a base station for use in a mobile telecommunicationssystem, wherein the circuitry comprises a controller element and atransceiver element configured to operate together to: transmit, to aterminal, first data in a set of identified resources allocated for thetransmission of the first data;

identify that a portion of the identified resources has been used totransmit data other than the first data; and

retransmit a subset of the first data, the subset of the first datacomprising the portion of the first data that was previously scheduledto be transmitted in the portion of the identified resources.

Example 27

Circuitry for a base station for use in a mobile telecommunicationssystem, wherein the circuitry comprises a controller element and atransceiver element configured to operate together to carry out themethod of any one of Examples 1 to 12.

Example 28

A method of using a terminal in a mobile telecommunications system, themethod comprising:

receiving transmission data in a set of identified resources allocatedfor the transmission of first data to the terminal;

identifying that a portion of the identified resources has been used totransmit data other than the first data;

receiving retransmission data corresponding to a subset of the firstdata, the subset of the first data comprising the portion of the firstdata that was previously scheduled to be transmitted in the portion ofthe identified resources;

attempting to decode the first data based on the transmission data andon the retransmission data;

Example 29

The method of Example 28 further comprising one or more of:

upon receipt of the transmission information, attempting to decode thefirst data and, in the event that the decoding of the first data isunsuccessful, transmitting an indication that the terminal has beenunable to decode the first data from the set of identified resources;identifying that a portion of the identified resources has been used totransmit data other than the first data upon receipt of an indicationthat the portion of the identified resources has been used to transmitdata other than the first data;transmitting retransmission indication for requesting that the subset ofthe first data corresponds exactly to the portion of the first data orthat the subset of the first data contains additional data compared tothe portion of the first data.

Example 30

A terminal for use in a mobile telecommunications system, the terminalbeing configured to:

receive transmission data in a set of identified resources allocated forthe transmission of first data to the terminal;

identify that a portion of the identified resources has been used totransmit data other than the first data;

receive retransmission data corresponding to a subset of the first data,the subset of the first data comprising the portion of the first datathat was previously scheduled to be transmitted in the portion of theidentified resources; and attempt to decode the first data based on thetransmission data and on the retransmission data.

Example 31

A terminal for use in a mobile telecommunications system, the terminalbeing configured to implement the method of Example 28 or 29.

Example 32

Circuitry for a terminal for use in a mobile telecommunications system,wherein the circuitry comprises a controller element and a transceiverelement configured to operate together to:

receive transmission data in a set of identified resources allocated forthe transmission of first data to the terminal;

identify that a portion of the identified resources has been used totransmit data other than the first data;

receive retransmission data corresponding to a subset of the first data,the subset of the first data comprising the portion of the first datathat was previously scheduled to be transmitted in the portion of theidentified resources; and

attempt to decode the first data based on the transmission data and onthe retransmission data.

Example 33

Circuitry for a terminal for use in a mobile telecommunications system,wherein the circuitry comprises a controller element and a transceiverelement configured to operate together to carry out the method ofExample 28 or 29.

REFERENCES

-   [1] RP-160671, “New SID Proposal: Study on New Radio Access    Technology,” NTT DOCOMO, RAN #71-   [2] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based    radio access”, John Wiley and Sons, 2009

What is claimed is:
 1. A retransmission method for use in a mobiletelecommunications system, the retransmission method comprising:controlling transmission, to a terminal, of first data in a set ofidentified resources allocated for the transmission of the first data;determining whether a portion of the set of identified resources hasbeen used to transmit data other than the first data during thetransmission of the first data; and controlling retransmission, to theterminal in a case that the determining indicates that the portion ofthe set of the identified resources has been used to transmit the dataother than the first data during the transmission of the first data, ofa subset of the first data without retransmission of a remainder of thefirst data.
 2. The retransmission method of claim 1, further comprising:receiving an indication that the terminal has been unable to decode thefirst data from the set of identified resources, wherein the determiningis performed based on receipt of the indication.
 3. The retransmissionmethod of claim 1, wherein upon determination by the terminal that theterminal is unable to decode the first data from the set of identifiedresources, the terminal attempts to decode the first data using at leasta part of the transmission received in the set of identified resourcesand using the retransmission of the subset of the first data.
 4. Theretransmission method of claim 1, wherein the portion of the set ofidentified resources has been used to transfer either only the dataother than the first data or both the first data and the data other thanthe first data.
 5. The retransmission method of claim 1, whereinretransmitting the subset of the first data comprises transmitting orretransmitting physical bits that were transmitted in the set ofidentified resources for sending the subset of the first data.
 6. Theretransmission method of claim 1, wherein retransmitting the subset ofthe first data comprises transmitting or retransmitting modulationsymbols for sending the subset of the first data in the set ofidentified resources.
 7. The retransmission method of claim 1, whereinretransmitting the subset of the first data comprises transmitting orretransmitting the subset of the first data using a retransmit ratematching procedure changing a robustness of the retransmission relativeto a robustness provided by a transmit rate matching procedure used forsending the first data.
 8. The retransmission method of claim 7, whereina rate-matching procedure is at least one of a physical bit ratematching procedure and a modulation symbol rate matching procedure. 9.The retransmission method of claim 1, wherein retransmitting the subsetof the first data comprises transmitting or retransmitting the subset ofthe first data using a first amount of resources that is different thana second amount of resources used for transmitting the subset of thefirst data in the set of identified resources.
 10. The retransmissionmethod of claim 1, wherein the set of identified resources is in a firsttime unit, and retransmitting the subset of the first data comprisesretransmitting the subset of the first data in a further set ofidentified resources, the further set of identified resources being asecond time unit subsequent to the first time unit.
 11. Theretransmission method of claim 1, wherein the transmission of the subsetof the first data is corrupted by the portion of the set of identifiedresources having been used to transmit the data other than the firstdata.
 12. A base station for use in a mobile telecommunications system,the base station comprising: circuitry configured to: controltransmission, to a terminal, first data in a set of identified resourcesallocated for the transmission of the first data; determine whether aportion of the set of identified resources has been used to transmitdata other than the first data during the transmission of the firstdata; and control retransmission, to the terminal in a case that thecircuitry determines that the portion of the set of the identifiedresources has been used to transmit the data other than the first dataduring the transmission of the first data, of a subset of the first datawithout retransmission of a remainder of the first data.
 13. The basestation of claim 12, wherein the circuit is further configured toreceive an indication that the terminal has been unable to decode thefirst data from the set of identified resources, and the circuitryperforms determination based on receipt of the indication.
 14. The basestation of claim 12, wherein upon determination by the terminal that theterminal is unable to decode the first data from the set of identifiedresources, the terminal attempts to decode the first data using at leasta part of the transmission received in the set of identified resourcesand using the retransmission of the subset of the first data.
 15. Thebase station of claim 12, wherein the portion of the set of identifiedresources has been used to transfer either only the data other than thefirst data or both the first data and the data other than the firstdata.
 16. The base station of claim 12, wherein the subset of the firstdata corresponds exactly to the portion of the first data.
 17. The basestation of claim 12, wherein the subset of the first data comprises morethan the portion of the first data.
 18. The base station of claim 12,wherein retransmitting the subset of the first data comprisestransmitting or retransmitting physical bits that were transmitted inthe set of identified resources for sending the subset of the firstdata.
 19. The base station of claim 12, wherein the transmission of thesubset of the first data is corrupted by the portion of the set ofidentified resources having been used to transmit the data other thanthe first data.
 20. A terminal for use in a mobile telecommunicationssystem, the terminal comprising: circuitry configured to: receivetransmission of data in a set of identified resources allocated for atransmission of first data to the terminal, the data being separate fromthe first data; determine whether a portion of the set of identifiedresources has been used to transmit the data other than the first dataduring transmission of the first data; receive retransmission, in a casethat the circuitry determines that the portion of the set of theidentified resources has been used to transmit the data other than thefirst data during the transmission of the first data, a subset of thefirst data without receiving retransmission of a remainder of the firstdata; and attempt to decode the first data based on the first datareceived in the transmission and the subset of the first data receivedin the retransmission.